Possibilities and constraints of implementing starch consolidated high speed steel in prototyping
Paper i proceeding, 2006

In the starch consolidation (SC) process, a water-based slurry containing powder, starch, dispersant and thickener is used to fabricate near net-shape green bodies that are de-binded and further consolidated by sintering. In this study, gas atomized M3/2 as well as high and low carbon V-rich M4 type high speed steel powder (<150 mu m) are considered, Both material types undergo high volumetric shrinkage during super-solidus liquid phase sintering enabling them to reach near full density. The analyses and the review cover different process aspects like: recipe optimisation, post-gelatinization drying, de-binding and sintering. A SC recipe consisting of 58 vol.% powder, 3 vol.% starch, 1 vol.% dispersant and a thickener solution resulted in a density of >98% than what is theoretically stated after sintering. It is found that the success of the post-gelatinization drying procedure depends on the smoothness of mould material and controlling powder oxidation. The best combination was freeze drying the slurry in a silicon rubber mould. For V-rich alloys a total or partial control of eutectic carbides in the final microstructure could be realized for vacuum and nitrogen sintering atmospheres, respectively.

super-solidus liquid phase sintering

starch consolidation



Henrik Borgström

Chalmers, Material- och tillverkningsteknik, Yt- och mikrostrukturteknik

P. Harlin

Högskolan i Dalarna

M. Olsson

Högskolan i Dalarna

T. Paiar

Universita degli Studi di Trento

Y. Wang

Karlstads universitet

Lars Nyborg

Chalmers, Material- och tillverkningsteknik

Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

0921-5093 (ISSN)

Vol. 475 1-2 34-38





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